Repetitive transcranial magnetic stimulation over the primary motor cortex disrupts early boost but not delayed gains in performance in motor sequence learning
; Peigneux, Philippe ; MAERTENS DE NOORDHOUT, Alain et al
in European Journal of Neuroscience (2008), 28(6), 1216-1221Detailed reference viewed: 9 (0 ULg)
The boundaries of consciousness: lessons from coma and related states
Laureys, Steven ; Boly, Mélanie ; Moonen, Gustave
in Advances in Clinical Neuroscience and Rehabilitation (2008), 8(2),Detailed reference viewed: 45 (12 ULg)
Time is brain: prise en charge de l'accident vasculaire cérébral ischémique à la phase aigue.
SADZOT, Bernard ; RIKIR, Estelle ; Moonen, Gustave
in Revue Médicale de Liège (2008), 63(5-6), 257-262Detailed reference viewed: 9 (2 ULg)
Intrinsic brain activity in altered states of consciousness: how conscious is the default mode of brain function?
Boly, Mélanie ; Phillips, Christophe ; Tshibanda, Luaba et al
in Annals of the New York Academy of Sciences (2008), 1129
Spontaneous brain activity has recently received increasing interest in the neuroimaging community. However, the value of resting-state studies to a better understanding of brain-behavior relationships ... [more ▼]
Spontaneous brain activity has recently received increasing interest in the neuroimaging community. However, the value of resting-state studies to a better understanding of brain-behavior relationships has been challenged. That altered states of consciousness are a privileged way to study the relationships between spontaneous brain activity and behavior is proposed, and common resting-state brain activity features observed in various states of altered consciousness are reviewed. Early positron emission tomography studies showed that states of extremely low or high brain activity are often associated with unconsciousness. However, this relationship is not absolute, and the precise link between global brain metabolism and awareness remains yet difficult to assert. In contrast, voxel-based analyses identified a systematic impairment of associative frontoparieto-cingulate areas in altered states of consciousness, such as sleep, anesthesia, coma, vegetative state, epileptic loss of consciousness, and somnambulism. In parallel, recent functional magnetic resonance imaging studies have identified structured patterns of slow neuronal oscillations in the resting human brain. Similar coherent blood oxygen level-dependent (BOLD) systemwide patterns can also be found, in particular in the default-mode network, in several states of unconsciousness, such as coma, anesthesia, and slow-wave sleep. The latter results suggest that slow coherent spontaneous BOLD fluctuations cannot be exclusively a reflection of conscious mental activity, but may reflect default brain connectivity shaping brain areas of most likely interactions in a way that transcends levels of consciousness, and whose functional significance remains largely in the dark. [less ▲]Detailed reference viewed: 84 (8 ULg)
Perception of pain in the minimally conscious state with PET activation: an observational study.
Boly, Mélanie ; Faymonville, Marie-Elisabeth ; et al
in Lancet Neurology (2008), 7(11), 1013-20
BACKGROUND: Patients in a minimally conscious state (MCS) show restricted self or environment awareness but are unable to communicate consistently and reliably. Therefore, better understanding of cerebral ... [more ▼]
BACKGROUND: Patients in a minimally conscious state (MCS) show restricted self or environment awareness but are unable to communicate consistently and reliably. Therefore, better understanding of cerebral noxious processing in these patients is of clinical, therapeutic, and ethical relevance. METHODS: We studied brain activation induced by bilateral electrical stimulation of the median nerve in five patients in MCS (aged 18-74 years) compared with 15 controls (19-64 years) and 15 patients (19-75 years) in a persistent vegetative state (PVS) with (15)O-radiolabelled water PET. By way of psychophysiological interaction analysis, we also investigated the functional connectivity of the primary somatosensory cortex (S1) in patients and controls. Patients in MCS were scanned 57 (SD 33) days after admission, and patients in PVS 36 (9) days after admission. Stimulation intensities were 8.6 (SD 6.7) mA in patients in MCS, 7.4 (5.9) mA in controls, and 14.2 (8.7) mA in patients in PVS. Significant results were thresholded at p values of less than 0.05 and corrected for multiple comparisons. FINDINGS: In patients in MCS and in controls, noxious stimulation activated the thalamus, S1, and the secondary somatosensory or insular, frontoparietal, and anterior cingulate cortices (known as the pain matrix). No area was less activated in the patients in MCS than in the controls. All areas of the cortical pain matrix showed greater activation in patients in MCS than in those in PVS. Finally, in contrast with patients in PVS, those in MCS had preserved functional connectivity between S1 and a widespread cortical network that includes the frontoparietal associative cortices. INTERPRETATION: Cerebral correlates of pain processing are found in a similar network in controls and patients in MCS but are much more widespread than in patients in PVS. These findings might be objective evidence of a potential pain perception capacity in patients in MCS, which supports the idea that these patients need analgesic treatment. [less ▲]Detailed reference viewed: 301 (20 ULg)
Le Locked-In Syndrome : la conscience emmurée
Bruno, Marie-Aurélie ; ; Schnakers, Caroline et al
in Revue Neurologique (2008), 164
The Locked-In syndrome(LIS) is deﬁned by: (i) the presence of sustained eye opening (bilateral ptosis should be ruled out as a complicating factor);(ii) preserved awareness; (iii) aphonia or hypophonia ... [more ▼]
The Locked-In syndrome(LIS) is deﬁned by: (i) the presence of sustained eye opening (bilateral ptosis should be ruled out as a complicating factor);(ii) preserved awareness; (iii) aphonia or hypophonia; (iv) quadriplegia or quadriparesis; and (v) a primary mode of communication that uses vertical or lateral eye movement or blinking. Acute ventral pontine lesions are its most common cause. Following such brainstem lesions patients may remain comatose for sometime and then gradually awaken, remaining paralyzed and voiceless, superﬁcially resembling the vegetative state. Background. – It has been shown that more than half of the time physicians fail to recognize early signs of awareness in LIS. Given appropriate medical care,life expectancy may be several decades but the chances of good motor recovery remain small. Eye-controlled computer technology now allows LIS patients to communicate and control their environment. Recent studies show that most LIS patients self-report meaningful quality of life and the demand for euthanasia is infrequent. Conclusion. – Patients suffering from LIS should not be denied the right to die – and to die with dignity –but also they should not be denied the right to live–and to live with dignity and the best possible pain and symptom management and revalidation. [less ▲]Detailed reference viewed: 61 (19 ULg)
Measuring the effect of amantadine in chronic anoxic minimally conscious state
Schnakers, Caroline ; Hustinx, Roland ; Vandewalle, Gilles et al
in Brain Injury (2008)Detailed reference viewed: 18 (1 ULg)
Consciousness and cerebral baseline activity fluctuations
Boly, Mélanie ; Phillips, Christophe ; Balteau, Evelyne et al
in Human Brain Mapping (2008), 29
The origin of within-subject variability in perceptual experiments is poorly understood. We here review evidence that baseline brain activity in the areas involved in sensory perception predict subsequent ... [more ▼]
The origin of within-subject variability in perceptual experiments is poorly understood. We here review evidence that baseline brain activity in the areas involved in sensory perception predict subsequent variations in sensory awareness. We place these ﬁndings in light of recent ﬁndings on the architecture of spontaneous BOLD ﬂuctuations in the awake human brain, and discuss the possible origins of the observed baseline brain activity ﬂuctuations. [less ▲]Detailed reference viewed: 12 (4 ULg)
Is there anybody in there? Detecting awareness in disorders of consciousness.
; Vanhaudenhuyse, Audrey ; et al
in Expert Review of Neurotherapeutics (2008), 8(11), 1719-30
The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and ... [more ▼]
The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and electrophysiological tools in search for objective markers of consciousness is being employed. However, such tools cannot be considered as diagnostic per se, but as assistants to the clinical evaluation, which, at present, remains the gold standard. Regarding therapeutic management in DOC, no evidence-based recommendations can be made in favor of a specific treatment. The present review summarizes clinical and paraclinical studies that have been conducted with neuroimaging and electrophysiological techniques in search of residual awareness in DOC. We discuss the medical, scientific and ethical implications that derive from these studies and we argue that, in the future, the role of neuroimaging and electrophysiology will be important not only for the diagnosis and prognosis of DOC but also in establishing communication with these challenging patients. [less ▲]Detailed reference viewed: 9 (0 ULg)
Voluntary brain processing in disorders of consciousness
Schnakers, Caroline ; ; et al
in Neurology (2008), 71(20), 1614-1620
Background: Disentangling the vegetative state from the minimally conscious state is often difficult when relying only on behavioral observation. In this study, we explored a new active evoked related ... [more ▼]
Background: Disentangling the vegetative state from the minimally conscious state is often difficult when relying only on behavioral observation. In this study, we explored a new active evoked related potentials paradigm as an alternative method for the detection of voluntary brain activity. Methods: The participants were 22 right-handed patients (10 traumatic) diagnosed as being in a vegetative state (VS) (n 8) or in a minimally conscious state (MCS) (n 14). They were presented sequences of names containing the patient’s own name or other names, in both passive and active conditions. In the active condition, the patients were instructed to count her or his own name or to count another target name. Results: Like controls, MCS patients presented a larger P3 to the patient’s own name, in the passive and in the active conditions. Moreover, the P3 to target stimuli was higher in the active than in the passive condition, suggesting voluntary compliance to task instructions like controls. These responses were even observed in patients with low behavioral responses (e.g., visual fixationand pursuit). In contrast, no P3 differences between passive and active conditions were observed for VS patients. Conclusions: The present results suggest that active evoked-related potentials paradigms may permit detection of voluntary brain function in patients with severe brain damage who present with a disorder of consciousness, even when the patient may present with very limited to questionablyany signs of awareness. [less ▲]Detailed reference viewed: 14 (1 ULg)
Revelations from the unconscious: studying residual brain function in coma and related states.
Laureys, Steven ; Boly, Mélanie ; Schnakers, Caroline et al
in Bulletin et Mémoires de l'Académie Royale de Médecine de Belgique (2008), 163(7-9), 381-8388-90
The purpose of our research is to contribute to a better understanding of the residual brain function of patients who survive an acute brain damage but remain in a coma, vegetative state, minimally ... [more ▼]
The purpose of our research is to contribute to a better understanding of the residual brain function of patients who survive an acute brain damage but remain in a coma, vegetative state, minimally conscious state or locked-in syndrome. The diagnosis, prognosis, therapy and medical management of these patients remain difficult. These studies are also of interest scientifically, as they help to elucidate the neural correlates of human consciousness. We here review our studies on bedside behavioral evaluation scales, electrophysiology and functional neuroimaging in these disorders of consciousness and conclude by discussing methodological and ethical issues and current concepts of the standards for care and quality of life in these challenging conditions. [less ▲]Detailed reference viewed: 19 (4 ULg)
Comment prédire l'évolution du coma post-anoxique?
Kirsch, Murielle ; Boveroux, Pierre ; Massion, Paul et al
in Revue Médicale de Liège (2008), 63(5-6), 263-268Detailed reference viewed: 162 (15 ULg)
Metabolic correlates of clinical heterogeneity in questionable Alzheimer’s disease
Salmon, Eric ; Lekeu, Françoise ; Garraux, Gaëtan et al
in Neurobiology of Aging (2008), 29
Thirty-four subjects with questionable Alzheimer's disease (QAD) were included in a 3-year prospective study and underwent neuropsychological testing and measurement of brain metabolism using FDG-PET at ... [more ▼]
Thirty-four subjects with questionable Alzheimer's disease (QAD) were included in a 3-year prospective study and underwent neuropsychological testing and measurement of brain metabolism using FDG-PET at entry. Seventeen patients (50%) did not convert to AD during the follow-up period. Compared to elderly controls of similar age, the cerebral activity of non-converters was reduced in the dorsolateral prefrontal cortex. Moreover, the variability of metabolism in the posterior cingulate cortex was related to their visuospatial memory performance, while disparity in parietal activity was related to their verbal memory performance. These results demonstrate the cerebral metabolic heterogeneity of patients with QAD. Initial functional images of converters showed that activity was already impaired in the posterior cingulate, lateral temporal cortex, anterior cingulate and orbitofrontal cortex. This metabolic pattern is consistent with a pre-dementia stage of AD, and highlights the fact that significant frontal metabolic involvement may be associated with impaired activity in posterior associative cortices in very early AD. [less ▲]Detailed reference viewed: 55 (12 ULg)
Spontaneous neural activity during human slow wave sleep.
Dang Vu, Thien Thanh ; Schabus, Manuel ; Desseilles, Martin et al
in Proceedings of the National Academy of Sciences of the United States of America (2008), 105(39), 15160-5
Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the ... [more ▼]
Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the previous awake period. At the cellular level, during SWS, a slow oscillation (<1 Hz) synchronizes firing patterns in large neuronal populations and is reflected on electroencephalography (EEG) recordings as large-amplitude, low-frequency waves. By using simultaneous EEG and event-related functional magnetic resonance imaging (fMRI), we characterized the transient changes in brain activity consistently associated with slow waves (>140 microV) and delta waves (75-140 microV) during SWS in 14 non-sleep-deprived normal human volunteers. Significant increases in activity were associated with these waves in several cortical areas, including the inferior frontal, medial prefrontal, precuneus, and posterior cingulate areas. Compared with baseline activity, slow waves are associated with significant activity in the parahippocampal gyrus, cerebellum, and brainstem, whereas delta waves are related to frontal responses. No decrease in activity was observed. This study demonstrates that SWS is not a state of brain quiescence, but rather is an active state during which brain activity is consistently synchronized to the slow oscillation in specific cerebral regions. The partial overlap between the response pattern related to SWS waves and the waking default mode network is consistent with the fascinating hypothesis that brain responses synchronized by the slow oscillation restore microwake-like activity patterns that facilitate neuronal interactions. [less ▲]Detailed reference viewed: 134 (27 ULg)
Mesurer la douleur chez le patient non communicant.
Chatelle, Camille ; Vanhaudenhuyse, Audrey ; Mergam, Anne-Nora et al
in Revue Médicale de Liège (2008), 63(5-6), 429-37
Pain is a subjective experience. Its assessment is based on the subject's direct verbal report. This method of assessment is, however, impossible in patients who cannot communicate their feelings. In this ... [more ▼]
Pain is a subjective experience. Its assessment is based on the subject's direct verbal report. This method of assessment is, however, impossible in patients who cannot communicate their feelings. In this context, indirect measurements such as behavioral observations or physiological measurements are needed. To facilitate the assessment of pain in non-communicative patients, numerous standardized behavioral scales have been developed. The aim of this review is to discuss the main validated pain scales employed in end-stage dementia, newborn and preverbal children, and severely brain damaged patients with a disorder of consciousness such as coma, the vegetative state or the minimally conscious state. [less ▲]Detailed reference viewed: 836 (20 ULg)
Que mesure la neuro-imagerie fonctionnelle: IRMf, TEP & MEG?
Gosseries, Olivia ; Demertzi, Athina ; Noirhomme, Quentin et al
in Revue Médicale de Liège (2008), 63(5-6), 231-7
Functional cerebral imaging techniques allow the in vivo study of human cognitive and sensorimotor functions in physiological or pathological conditions. In this paper, we review the advantages and ... [more ▼]
Functional cerebral imaging techniques allow the in vivo study of human cognitive and sensorimotor functions in physiological or pathological conditions. In this paper, we review the advantages and limitations of functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and magnetoencephalography (MEG). fMRI and PET measure haemodynamic changes induced by regional changes in neuronal activity. These techniques have a high spatial resolution (a few millimeters), but a poor temporal resolution (a few seconds to several minutes). Electroencephalogram (EEG) and MEG measure the neuronal electrical or magnetic activity with a high temporal resolution (i.e., milliseconds) albeit with a poorer spatial resolution (i.e., a few millimeters to one centimeter). The combination of these different neuroimaging techniques allows studying different components of the brain's activity (e.g., neurovascular coupling, electromagnetic activity) with both a high temporal and spatial resolution. [less ▲]Detailed reference viewed: 185 (19 ULg)
Measuring the effect of amantadine in chronic anoxic minimally conscious state.
Schnakers, Caroline ; Hustinx, Roland ; Vandewalle, Gilles et al
in Journal of Neurology, Neurosurgery & Psychiatry (2008), 79(2), 225-7Detailed reference viewed: 40 (5 ULg)